2

i was wondeiring that if Copy() and Clone() method do the same task whats diffrence between them and which one to use

as per what i have searched aboout is that clone() makes a new string and copy() just do copy an existing string and use it

if this is correct than which one is better

  • 2
    There really isn't a good reason to use either method, tbh. – Dai Jul 22 '22 at 05:13
  • `string` is `ICloneable`, by not actually cloning anything. It just returns itself. `string.Copy()` is pointless, sure it creates a new string, but you can only tell via `Object.ReferenceEquals`. – Jeremy Lakeman Jul 22 '22 at 05:16
  • In c# strings are Immutable - that means by default you never pass refs around, but the raw data each time. To copy or clone a string just go var string1 = string2; using the copy and clone methods will just add confusion – The Lemon Jul 22 '22 at 05:17
  • Did you read the documentation? [Clone](https://learn.microsoft.com/en-us/dotnet/api/system.string.clone) will not do anything, while [Copy](https://learn.microsoft.com/en-us/dotnet/api/system.string.copy) _might_ create a new instance with the same value, or sometimes not. – Klaus Gütter Jul 22 '22 at 05:18
  • 1
    @TheLemon yes, string is immutable. But you still pass refs around, not copies of the string contents. "equals" is overridden to perform a value equality instead of the default ref-equality – Hans Kesting Jul 22 '22 at 06:07

1 Answers1

5

TL;DR:

Don't use either method:

  • Clone doesn't actually do anything.
  • Copy is officially obsolete.

Etc:

I'll preface my answer by saying that because String values are immutable there aren't really many (or any?) good reasons for using either String.Clone() or String.Copy.

as per what i have searched aboout is that clone() makes a new string and copy() just do copy an existing string and use it

Sorry but your understanding is incorrect.

As per the documentation (emphasis mine):

String.Clone() does not create a copy of the string, in fact it just returns a self-reference:

https://learn.microsoft.com/en-us/dotnet/api/system.string.clone?view=net-6.0

The return value is not an independent copy of this instance; it is simply another view of the same data. Use the Copy or CopyTo method to create a separate String object with the same value as this instance.

Because the Clone method simply returns the existing string instance, there is little reason to call it directly.

As for String.Copy():

https://learn.microsoft.com/en-us/dotnet/api/system.string.copy?view=net-6.0

The Copy method returns a String object that has the same value as the original string but represents a different object reference.

[...]

Starting with .NET Core 3.0, this method is obsolete. However, we do not recommend its use in any .NET implementation. In particular, because of changes in string interning in .NET Core 3.0, in some cases the Copy method will not create a new string but will simply return a reference to an existing interned string.

Additionally, because String.Copy might create a copy (depending on how interning works)_ it means it's a O(n) operation.

Dai
  • 141,631
  • 28
  • 261
  • 374